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> Regearing for a longer 5th gear, is it a reasonable thing to do?
SGB
post Nov 28 2006, 08:14 PM
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(IMG:style_emoticons/default/piratenanner.gif)
I'm getting a tranny for christmas! (IMG:style_emoticons/default/chair.gif)

(IMG:style_emoticons/default/chairfall.gif)
no really, DR EVIL is rebuilding the ol' 901 for me, and I've been thinking
(IMG:style_emoticons/default/bootyshake.gif)
with my brain that a longer 5th gear would be really nice.
(IMG:style_emoticons/default/driving.gif)

With a speed limit of 70 (usually traveled by EVERYONE at 80), my car gets pretty buzzy after a while.

I know it can be done, and if I ever was going to do it....
A flipped 904 "I" 5th gear might work.... of course I've already been advised that cubic dollars are needed AND another mainshaft.
I'm just dreamin'... Somebody slap me with a reality stick. What else would be involved in this? Who has details? Or better, who has a 904 5th gear lying around needing a home?
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Aaron Cox
post Nov 28 2006, 08:15 PM
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with at type 4 bad idea...

what size tires?

ZD with short tires should keep you in the 3000 rpm range at 70...

bad idea
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Aaron Cox
post Nov 28 2006, 08:16 PM
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BTW - you flip a second gear from a 4 speed 901/902 to get a taller 5th

2nd in a 4 spd... is the same position as third in a 5 speed...
THUS the flipped 5th into 3rd for a short third (i love it)

what size tires? are you gonna make me post my chart again?

you wont cool well enough at high speeds without some rpm to turn the fan.....
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SGB
post Nov 28 2006, 08:17 PM
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They are 50 series tires. Is ZD what is in there now?
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Aaron Cox
post Nov 28 2006, 08:19 PM
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ya made me do it!

here is the chart i config'd for my motor/gears/tire size

grey shading is stock gears....
A F N V ZD

ill try and find the one with the flipped H,HA, and HB gears....


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SGB
post Nov 28 2006, 08:19 PM
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I've alway had fine cooling, and could compensate with bigger main jets in the webers.I wanna see that chart? Is it big and UGLY? WIll it shut me up?
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SGB
post Nov 28 2006, 08:20 PM
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AAAARGGHH!!!
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SGB
post Nov 28 2006, 08:21 PM
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but

its

kinda
COOL.
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Aaron Cox
post Nov 28 2006, 08:22 PM
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your head temps will go up with less RPM turning the COOLING fan (IMG:style_emoticons/default/smile.gif)
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Dr Evil
post Nov 28 2006, 08:27 PM
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ZD is what is in there now. I do not see how smaller tires will cause lower RPMs, Aaron (IMG:style_emoticons/default/huh.gif) If you put larger profile tires on your car you will lower your RPMs, not the other way around. Like a said before, you should be at 4000rpm at 89MPH in stock form. the 50 series tires should only bump the RPMs up a bit. Our engines are not like the water cooled type. Air flow is life, thus higher RPM under load at fast speeds = better cooling and less fatigue on your engine. This is why long hills on hot days are particularly bad for our cars (more so than many other scenarios). Lots of demand, hard to keep up RPMs AND speed. If you want to know what it will be like to drive with a taller fifth gear just go for a long drive up a steep hill (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/wink.gif)

<:edited because Aaron posted the damn chart first (IMG:style_emoticons/default/rolleyes.gif) :>
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Aaron Cox
post Nov 28 2006, 08:29 PM
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QUOTE(Dr Evil @ Nov 28 2006, 06:27 PM) *

ZD is what is in there now. I do not see how smaller tires will cause lower RPMs, Aaron (IMG:style_emoticons/default/huh.gif) If you put larger profile tires on your car you will lower your RPMs, not the other way around. Like a said before, you should be at 4000rpm at 89MPH in stock form. the 50 series tires should only bump the RPMs up a bit. Our engines are not like the water cooled type. Air flow is life, thus higher RPM under load at fast speeds = better cooling and less fatigue on your engine. This is why long hills on hot days are particularly bad for our cars (more so than many other scenarios). Lots of demand, hard to keep up RPMs AND speed. If you want to know what it will be like to drive with a taller fifth gear just go for a long drive up a steep hill (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/wink.gif)

Here is Aarons chart for those of you watching at home and wandering where we pull these numbers from (IMG:style_emoticons/default/biggrin.gif)


taller gear = less rpm.
less rpm = less cooling.
shorter tire = MORE rpm

i dont think i said that mike....
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SGB
post Nov 28 2006, 08:32 PM
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I'm trying to grasp this with my little tuna-like brain and I gotta ask- the colored bands- yellow is 50 series? At 5K? OK, the flipped 904 2nd gives a 0.61 in place of 0.71 for the ZD. That doesn't seem too drastic...
(I'm a stubborn ol' fishhead)
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Dr Evil
post Nov 28 2006, 08:33 PM
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Now now Aaron, dont get testy (IMG:style_emoticons/default/wink.gif) I reread your post and relized what you were saying with the 3K at 70mph and 50 series tires.
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Aaron Cox
post Nov 28 2006, 08:34 PM
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click the picture... it gets bigger...

if you look at the top.. you can see it is setup for a 23.59" tire.... (225/50/15)
and a 205 50 is slightly smaller 23.0" so the rpms will be SLIGHTLY more than what is pictured....
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SGB
post Nov 28 2006, 08:45 PM
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Of course I realize you know what you are talking about (both of ya). It is just a pipe dream (IMG:style_emoticons/default/smile.gif)

The 50 tires cretainly seemed to make a profund impact on the admitidly already innacurate speedo readings-
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Aaron Cox
post Nov 28 2006, 09:10 PM
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QUOTE(SGB @ Nov 28 2006, 06:45 PM) *

Of course I realize you know what you are talking about (both of ya). It is just a pipe dream (IMG:style_emoticons/default/smile.gif)

The 50 tires cretainly seemed to make a profund impact on the admitidly already innacurate speedo readings-


9% shorter than stock....

the MPH's on the chart are ACTUAL speed... not indicated

your speeds will be 1-2% lower than the chart.. (same as saying your RPM's will be a few% higher at the same speed)
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jwalters
post Nov 28 2006, 09:15 PM
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Can first gear be flipped for a new fifth??











(IMG:style_emoticons/default/ph34r.gif)
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Aaron Cox
post Nov 28 2006, 09:18 PM
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no bozo (IMG:style_emoticons/default/smile.gif)

you have a few choices for first gears
A
AA
B
C
D

A is stock on most 911's and all 914's
AA harder to find... a few hundred bucks...
B/C/D hens teeth. good luck with that.
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Dr Evil
post Nov 28 2006, 09:18 PM
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Nope. I was wondering the same thing once, but you would have to machine it and I do not think that there would be enough meat.
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jwalters
post Nov 28 2006, 09:18 PM
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Sooo Close.......
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I clicked the picture - it got smaller.

Couldn't read it anymore.

Even with my coke bottle glasses and nose plastered on the screen.











I really gotta learn 'puters.





So, how again do you get a taller fifth? You guys lost me -
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